Spark-plug.



1. A. DE'vl-Lsnss.

ASPARK PLUG. APPLICATION FILED IUNE 2.1917.

fatented Nov. 20, 1917 y un En STATES PATE JOHNA. DE v'ILBIss, or sr.l LoUIs, MISSOURI, AssIGivoR'To HENRY L. BOUDBEAU, or

ST. LOUIS, MISSOURI.

. SPARK-MUG.

Specification of ietters Patent. Patented N 0V. 20, 1917.

Application led .Tune 2, 1.917. Serial'No. 172,436.

To all whom t may concern.'

Be it known that I, JOHN A. DE VILBIss,v

a citizen of the United States, residing at St. Louis, Missouri, have invented a. certain new and useful Improvement in Spark' Plugs, of which thefollowing is a full, clear, and exact description, such as will enable others skilled inthe art to which it appertains to make and use the same.

This invention relates to al spark plug of D 42o apracticable commercial spark plug of the eneral type referred to that can be manuactured at a low cost and Whose external 'dimensions are practically the same as the standard spark plugsnow in general use. Another object isto provide a'spapk plug in which one or more gravity seated check valves are mounted in the body portion of the plug in such a manner thatl they `can be retained in operative position either by the v insulatoror by amember interposed between the insulator and the body portion of the plug. Other objects and desirable features of my invention will vbe hereinafter pointed' out.

Figure l of the drawings is a vertical sectional view, illustrating a spark plug constructed in -accordance with my present invention; and

Fig. 2 is a bottom plan view of the spark 40 plug shown in Fig. 1.1

Referring to the drawings, which villustrate the preferredform of my invention, A designates the metal body part of the plug, which ispreferably formed from standard bar iron, B designates the insulator vand C designates the contact carried by the insulator and projecting downwardly through' the cavity or center opening in the metal body part of the plug. The plug is equipped with one or a plurality of gravity seated check valves which are so arranged thatfresh air will be drawn into the center space .or cavity a: in the metal body part of the plug when the plug is inuse,and thus prevent soot from-collectingand remaining on part from v the insulator, on the inner wall of the cavity x, or on the terminals of the plug. The sparkplug herein`illustrated is provided with two gravity seated ball check Valves D, but it is not essential that a ,plurality of check valves be employed, as a single check valve, properly' constructed, will effectively prevent carbon from collecting on the interior of the plug. Each of the check valves consists of a ball that is mounted in a ver- -tically-disposed bore 1 formed inthe metal body part of the plugin close proximity tov the center cavity w, said bore being arranged intermediatethe ends of an air duct or passageway that leads from the center space or cavity to the exterior ofthe metal body .part of the plug. One convenient way of constructing the plug is to form the-body a section of standard bar iron, drill a vertical hole a in the upper end of same, and then counterbore-said-hole, so as to form the bore l in which the ball check valve `l) is arranged. A horizontally-disposedor inclined hole a is drilled in the side of the'metal-body part of the plug adjacent 80 the upper end of same, `so as to connect with thehole a, thus forming an air duct or pasl sageway that leads from the lower end of the bore l to the exterior of the metal body part ofthe plug. By constructing the plug in this manner I am able lto make the body part .in an automatic machine practically in one operation, thus producting the body part at a low cost. The insulator B is pro` vided with a reducedV extension that projects into the center space or cavity and the lower end of said insulator is preferably spaced away from the upper end ofthe metal body part A by means of a gasket or packing t element 2, so as toform an air .passageway 9'5 or duct that leads from the uppe'r end of the bore 1 to the cavity in the metal body part of the plug. -It is not essential, 'however, that the connection between thel bore r and cavity' be produced in this manner, as said bore and cavity could be connected in various other ways without departing from the spirit of my invention. vThe insulator B can be combined with the. metal body. part of theplug in any suitable way without departing from Vthe spirit of my invention,` but I prefer to providethe metal body part with a sleeve or annular extension 3 whose upper end portion 3a is flanged or turned over, so as to engage a gasket or packing element 2a 110 that is mounted on a laterally-projecting flange 4 on the Ainsulator B, thereby perinaneiitly connecting the insulator and metal body part together and.1 forming a gas tight joint between saidl parts. vThe gasket 2 not only serves to hold the .lower end of the insulator B spaced away from the upper end of the metal body part A, but it alo serves as an abutment that limits the upward movement of the check valves D, said gaskt being arranged in operative position after the check valves D have been introduced into the bores 1 in the metal body part of the plug.

lhen the engine on Awhich the plug is used is. in operation, the check valves D will be unseated when the piston moves in one direction, thereby causing fresh air to be drawn into the centerspace or cavity :c in the metal body part of the plug. .When the piston movesl in the opposite direction the valves D: will seat by gravity, owing tothe vfact that they are arranged in verticallydisposed bores formed in the body part of the plug.. The fresh air that is drawn into the cavity w causes the interior of the plug to be thoroughly scavenged, and said air also revents soot from collecting and remaining on the insulator, on the contact C, or on the inner wall' of the cavity :a Sonie of the Jfresh air that enters the cavity on the suction stroke of the piston remains in said cavity and becomes trapped in the upper end' portion of same on the succeeding compression stroke of the piston, the'check valves being arranged close enough to the upper end of said cavity to insure a blanket of compressed air at the base of the extension I) on the insulator. is .thereafter exploded yat the end' of the compression stroke, this trapped air acts as an air Vcushion which el'ectively prevents carbon' from collecting in the upper portion of the cavity or centerspace fr, exterior of the extension b of the insulator, or on the interior of the portion of the nietal body part A thav surrounds saine.4

A spark plug of the construction above described can be manufactured practically as cheaply as spark plv oi the kind nowv in general use which are not equipped with means for admitting fresh air to the -inta rior of thel plug, owing to the fact that the body portion of saine is formedfioni standard bar iron which can be machined in an automatic machine and the check valves are retained in operative positioiieitlier by the insulator or by the gasket arranged between the insulator and the body part. Another: desirable feature of my improved 1 plug that tlie external dimensions o' are practically the sa as the S spark plugs now in g nl use, l valves being complet ,l

metal part otwfplug, instcaV check valve in said bore, Isaid body part that laps over When the charge either on the` It is immaterial, so far as my broad idea which the air is drawn into is concerned, how the terminal or terminals on the metal body part are formed, but I prefer to provide the metal body part A at its lower end with a sleeve or annular extension 5 in which transverse vslots 6 are formed, so as to permitone or more of the portions that lie between said slots to be bent inwardly toward the lower end of the contact C, so as to form'one or more terminals 7.

vHaving thus described my invention, what I claim, and desire to secure by Letters Patent, is:l

1. A spark plug for internal combustion engines, comprising a symmetrical body part provided with a center space or cavity and with a vertically-disposed bore formed in the'upper end of saidbody part ita close proximity to said cavity, said bore communicating with said 'cavity and with Yan air inlet passageway in said body part, a ball an insulator on the upper end of said bore, and an extension on said insulator that projects into said cavity.

2. A spark plug for internal combustion engines, comprising a m talbody part freefrom lateral projections 'and extensions and provided with a center space or cavity, an insulator carried by said body part, a vertically-disposed bore' formed in' said body part at a` oint between said cavity and the outer 'sur ace of said body part and come 'les niunicating with said cavity, a ball check' 3. A spark plug for linternal combustion engines, comprising a. metal body part pro-' vided with a cavity or center space,l an-ill"` A sulator having a reduced extension that pro' jects into said cavity,

per end of said body `par?J air duct or passageway, posed bore in said bodypartwhich communicates at its upper end with said passageway, a gravity seated ball in said bore, and an air duct in said body part thatv leads from the llower end of said bore the exterior 'of said body part; for

purpose described.

a.' A spark plug-for internal combustion engines, comprising a nieta-l body part providedwith a center space or cavity, an in4 sulator having a reduced extension that proff,

so as to form ani check valve the lower side of said-"vinsiilator being spaced. away from the upa vertically-disim, e

.ing from the lower end of said bore to the 'zexterior' of said body part, a gravity seated ball check valve arranged in 'said' bore, aV

v combined packing and spacing element arranged between the underside of said insulator and the upper end of said body part in such a manner that it serves as an labutment which limits the upward movement of said check valve, and means for connecting said insulator to said body part.`

5. A spark plug for internal combustionA engines, comprising a metal body part provided with a center bore' or cavity, an insula-v tor provided with a reduced extension that projects into said cavity, a contact on said in- '.sulator that projects downwardly through said cavity, a sleeve on the lowerend of said body part provided with a portion that is bent inwardly toward said contact so as to forma terminal, a plurality 'of gravity seated ball i check valves arranged in said body part for causing fresh air to be admitted to said cavity intermittently when the plug is in use, and a ortion on the upper end of saidbody v part t at is anged over the insulator so as to secure the irnulator to said body art.

JOHN AL DE .VIL ISS. 

